AES Berlin 2014Engineering Brief EB4

EB4 - Papers Session 2

EB4-1 Creating Dynamic Psychoacoustic Maps of Hearing Threats for Outdoor Concerts Employing Supercomputing Grid—Jozef Kotus, Gdansk University of Technology - Gdansk, Poland; Maciej Szczodrak, Gdansk University of Technology - Gdansk, Poland; Karolina Marciniuk, Gdansk University of Technology - Gdansk, Poland; Andrzej Czyzewski, Gdansk University of Technology - Gdansk, Poland; Bozena Kostek, Gdansk University of Technology - Gdansk, Poland; Audio Acoustics Lab.The auditory effects caused by the outdoor concert are discussed in this paper. The analysis is based on the computation results obtained by means of supercomputing PL-Grid infrastructure and specific computational algorithms developed by the authors. The software consists of the outdoor sound propagation module and psychoacoustical noise dosimeter. The simulation was performed by means of real music recordings and the following outdoor propagation conditions were taken into account: speaker directivity, ground effect, building reflection, distance attenuation, and sound absorption by the atmosphere. On the basis of the proposed methodology the dynamic (one minute time resolution) psychoacoustic maps of hearing threats for considered area were created expressed by TTS (Temporary Threshold Shift) values in critical bands. Moreover, the results include also maps of sound level and noise dose values.
Engineering Brief 150 (Download now)

EB4-2 APE: Audio Perceptual Evaluation Toolbox for MATLAB—Brecht De Man, Queen Mary University of London - London, UK; Joshua D. Reiss, Queen Mary University of London - London, UKWe present a toolbox for multi-stimulus perceptual evaluation of audio samples. Different from MUSHRA (typical for evaluating audio codecs), the audio samples under test are represented by sliders on a single axis, encouraging careful rating, relative to adjacent samples, where both the reference and anchor are optional. Intended as a more flexible, versatile test design environment, subjects can rate the same samples on different scales simultaneously, with separate comment boxes for each sample, an arbitrary rating scale, and various randomization options. Other tools include a pairwise evaluation tool and a loudness equalization stage. We discuss some notable experiences and considerations based on various studies where these tools were used. We have found this test design to be highly effective when perceptually evaluating qualities pertaining to
music and audio production.
Engineering Brief 151 (Download now)

EB4-3 Principals of a Tunable Diaphragmatic Bass Absorber—Philippe Jeansonne, McGill University - Montreal, QC, Canada; Centre for Interdisciplinary Research in Music Media and Technology (CIRMMT) - Montreal, QC, CanadaOnce propagated in air, low frequency energy can be difficult to attenuate without physically prominent bass absorbers. The tunable diaphragmatic bass absorber fulfills this task in a discrete way. Mounted on an aluminum frame, a tunable membrane is separated by a thin air-gap to a layer of acoustic fibergalss. The membrane's excitation is restricted by the layer of acoustic fiberglass resulting in attenuation of a desired range of low frequencies. The proposed use for this new design is to attenuate a particular LF room mode or its harmonic.
Engineering Brief 152 (Download now)

EB4-4 A Motorized Telescope Mount as A Computer-Controlled Rotational Platform for Dummy Head Measurements—Matthew Shotton, BBC R&D - London, UK; Chris Pike, BBC Research and Development - Salford, Greater Manchester, UK; University of York - Heslington, York, UK; Frank Melchior, BBC Research and Development - Salford, UKThis paper covers the construction and validation of an affordable and accurate two degree-of-freedom rotational mount for making HRTF (head-related transfer function) and BRIR (binaural room impulse response) measurements using a dummy head microphone. We review the design requirements for a rotational mount in the context of measurements for binaural rendering, with reference to perceptual factors. In order to achieve a low-cost solution, we evaluate the suitability of a motorized telescope mount. Issues considered during design of the system are discussed. The use of affordable electronics to convert the mount into a general-purpose computer-controlled rotational platform is presented, as well as objective measurements to validate performance. Finally the limitations of this system are discussed and further use cases proposed.
Engineering Brief 153 (Download now)

EB4-5 Measurements and Visualization of Sound Intensity around the Human Head Using Acoustic Vector Sensor—Jozef Kotus, Gdansk University of Technology - Gdansk, Poland; Magdalena Plewa, Gdansk University of Technology - Gdansk, Poland; Bozena Kostek, Gdansk University of Technology - Gdansk, Poland; Audio Acoustics Lab.Measurements and visualization of sound intensity around a human head are presented in this paper. The sound intensity field was obtained by means of a Cartesian robot that was applied to precise positioning of the acoustic vector sensor. Measurements were performed in the free field using a head and torso simulator and a configuration of either one, two, or four loudspeakers. The acoustic vector sensor was positioned around the head with 5 cm step. Sound intensity was measured in 277 points. During every step the three orthogonal sound intensity components were calculated. Tonal signals for frequencies: 250, 500, 1000, 2000, 4000, and 8000 Hz were applied. Obtained results
were used to prepare visualizations of sound intensity distribution around the human head.
Engineering Brief 154 (Download now)